This invention relates to battery plates, particularly to generally planar flat sheet perforated lead grid substrate for pasted lead-acid battery plates.
It is known to form lead-acid accumulator grids by forming lead into sheets and then slitting and stretching the grid to form an expanded mesh. The expansion process involves considerable cold working of the lead which leads to corrosion of the grid. However, the expanded grid provides a good captivating matrix for the paste to reduce shedding. Also, because of the ability of the expanded grid to undergo a reduction in thickness, the continuous pasting of the grids is facilitated. Perforated lead grid, on the other hand, in which a flat lead sheet of substantially non-distortable thickness is perforated, stamped, rolled or slit to form apertures therein defining a mesh or grid structure, experiences reduced corrosion rates, as compared with expanded grid since less cold working of the lead takes place in the forming process. However, flat perforated grid is more difficult to paste, particularly with respect to driving the grid through the paster, and there is a lessened capability of the grid to fully captivate and retain the paste within the grid structure.
It is a primary object of the subject invention to produce a lead grid which combines the advantages of each of the expanded mesh and perforated types of lead grids.